1. Technical Field
The disclosure relates to a blowby gas treatment device that discharges blowby gas to an intake passage from inside an internal combustion engine, an intake manifold provided in an internal combustion engine, and an internal combustion engine.
2. Description of Related Art
A blowby gas treatment device is provided with an engine gas passage and an intake manifold gas passage, which serve as a passage in which blowby gas passes and are referred to as a blowby gas passage herein below. The engine gas passage is formed integrally with an internal combustion engine, for example, a cylinder head. The intake manifold gas passage is formed integrally with an intake manifold. Inside of the internal combustion engine and an intake passage formed inside the intake manifold are made to communicate with each other by the blowby gas passage. Then, blowby gas is discharged to the intake passage. The blowby gas passage is provided with a flow control valve for controlling an amount of blowby gas discharged to the intake passage through the blowby gas passage.
Japanese Patent Application Publication No. 2013-151872 discloses a passage serving as the blowby gas passage that extends inside an internal combustion engine and allows inside of a cylinder head and inside of a crankcase to communicate with each other.
The blowby gas treatment device monitors pressure in a part of the blowby gas passage on a downstream side of the flow control valve in a gas flow direction. This makes it possible to perform an operation check of the blowby gas treatment device. The operation check is performed, for example, as described below.
In the blowby gas treatment device, the part of the blowby gas passage on the downstream side in the gas flow direction is connected with the intake passage. As the flow control valve, a valve is frequently used, which opens when pressure in the downstream part becomes lower than pressure in a part of the blowby gas passage on an upstream side in the gas flow direction, which is referred to as an upstream part herein below. This means that many of these flow control valves open and close in accordance with a pressure difference between the downstream part and the upstream part. In the blowby gas treatment device, in which such a flow control valve is used, gas inside the downstream part of the blowby gas passage is sucked, and internal pressure of the downstream part is monitored. It is thus possible to perform operation check of the blowby gas treatment device.
Due to the suction of gas, internal pressure of the downstream part of the blowby gas passage is reduced, and the flow control valve opens properly. Then, pressure inside the engine is introduced into the downstream part from the upstream part. Therefore, pressure in the downstream part does not become so low. On the contrary, when the flow control valve remains closed and does not open even though internal pressure of the downstream part of the blowby gas passage is reduced by the suction of gas, pressure inside the engine is not introduced into the downstream part. Therefore, pressure in the downstream part is reduced greatly. By monitoring internal pressure of the downstream part of the blowby gas passage, it is possible to perform operation check of the blowby gas treatment device, namely, the flow control valve.
When performing this kind of operation check of a blowby gas treatment device having a structure in which an engine gas passage and an intake manifold gas passage are connected with each other through a hose, it is possible to disconnect the hose and connect the hose with operation check equipment. This means that it is possible to monitor pressure inside the blowby gas passage by a simple procedure.